Range of spectroscopies used in catalyst research

Espinosa Alonso, a chemist from Utrecht University, The Netherlands, used four different spectroscopic techniques to study catalysts in the course of their preparation: UV-vis-NIR-microspectroscopy, IR microspectroscopy, magnetic resonance imaging (MRI) and tomographic energy dispersive diffraction imaging (TEDDI). Whilst MRI and TEDDI are already frequently used in other research fields, but they are not commonly used to study the preparation of catalysts.

Thanks to the various techniques, Espinosa Alonso succeeded in following the preparation of the materials in space and time. This time and space resolution was needed because the active particles in the catalyst bodies did not stay in the same place throughout the entire preparation process. The ultimate performance of the catalyst depends, however, on where these active particles are situated. Being able to monitor and influence these movements is therefore vital.

The active particles can be distributed in a number of ways: they might be spread uniformly across the whole catalyst body, or cling like an eggshell to the outer surface, or sit in a wide ring like an egg white within the body, and they can even be found like a yolk in the middle of the egg. So, although the ingredients are exactly the same, the distribution makes a world of difference: for instance, lots of catalysts are ineffective if the particles are situated around the edge.

Espinosa Alonso managed to study this distribution in detail for each type, and even managed to alter the distribution of palladium in an alumina pellet from “eggshell” to “egg yolk”. She also managed to distribute nickel as an “eggshell”, which is extremely difficult. Thanks to her insights, new and improved catalysts can now be developed.

Her PhD research was undertaken in the Advanced Sustainable Processes by Engaging Catalytic Technologies (ASPECT) programme, which focuses on the catalysis of chemical processes in the bulk chemicals industry with the aim of increasing the sustainability of these processes. ASPECT is part of the NWO organisation ACTS (Advanced Chemical Technologies for Sustainability).

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